Electric heater system



Oct. 30, 1928.

w.' G. HARTWIG ELECTRIC HEATER SYSTEM Original Filed April 9, 1923 2 Sheets-Sheet l Oct. 30, 1928.

W. G. HARTWIG ELECTRIC HEATER SYSTEM Original Filed April.v 9, 1923 2 Sheets-Sheet Patented Oct. 30, 1928.

UNITED STATES i WILLIAM G. HARTWIG, F CHICAGO, ILLINOIS.

ELECTRIC HEATER SYSTEM.

yApplication led April 9, 1923, Serial No. 630,731.

My invention relatesy to thermostatically controlled electric heater systems such as are commonly installed in trolley cars and the like, andthas for its object the protection of the system in case of the accidental grounding of any of the heaters.

The invention may best be understood from the'following description of a preferred installation. It is to be understood, however,

that the specific disclosure is for the purpose of exemplification only and that the scope of the invention is defined in the following claims, it being my intention to secure thereby whatever invention is disclosed, in its broadest scope.

In the drawings accompanying and forming a part of this specification Fig. 1 is a diagrammatic view showing a complete heater systemembodying my4 invention in its preferred form; Fig. 2 is a vertical section of the automatic cutout thereof on a plane parallel to thesupporting panel, and Fig. 3 a ver- "tical section at right angles to the plane of Fig. 2 on the line 3 3 thereof.

` Referring first to the diagram shown in Fig. 1, it will be observed that the electric `heaters 4 are arranged in two circuits, there being six heaters in each circuit in this particular instance, the respective circuits being to the movable member 7 of the contactor. The stationary member 8 of the contactor is connected to line as shown. The movable member 7 is controlled by an electro-magnet 9, shown diagrammatically, which, 'when the temperature in the car or other compartment heated by the System is below the desired temperature for which the thermostat of the system is set, is energized from the line through a circuit comprising wire 10, resistor 11, wire 12, winding 13, wire 14, fuse 15 and ground 16. A thermostat 17 is connected in shunt to the operating coil of the contactor and adapted to short-circuit the latter when the temperature of the compartment in which the system is located rises to the maximum for which it `is designed. A'condenser 18 connected across the terminals of the thermostat reduces sparking on the opening of the thermostat switch.` A hand-switch 19 may also be utilized when desiredto short-circuit the( coil of the contractor.l

The automatic cut-outto which the invention more particularly relates, is indicated at a; 20 in the diagram but. will be mure specifi@ fused at 5 and jointly connected by wire'6 Renewed February 25, 1927.

cally described in connection with Figs. 2 and 3. The movable and stationary contacts 21, 22 of the cut-out are connected across the terminals of the contacter coil as best seen in Fig. 1. The stationary contact is carried by a bracket 23 mounted on the panel and the movable contact is carried by an arm 24 hinged to a bracket 25 mountedon the panel as seen in Figs. 2 and 3. The arm is gravity-operated and when it is not sustained by the device to be presently described drops to close the .shunt circuit, whereby the contactor is caused to open the heating circuit. y

The device for normally holding the automatic cut-out switch open and which constitutes the present invention comprises an inverted `T-shaped latch 26 which is pivotally and bodily movable upon the panel and the central limb of which normally supports the 'arm 24 in a position in which the automatic cutout is open. It is mounted upon an vangleiron or bracket 27 by means of a screw-pin 28 on such bracket which extends through a slot 29 in the latch. The angle-iron 27 is supported by a sheet-metal bracket 28 attached to the panel. An insulating block 30 is secured to the under-face ofthe arm 24 and normally rests upon the upper end of the latch. When the latch `is tilted to either side of the central position, as in case of the grounding of any of the heaters, it permits the arm to drop to close the switch. The latch extends through an opening 31 in bracket 28 of proper dimensions to .permit but limit the swing of the latch in either direction from the central position shown. The lateral arms of the latch arenotched at 32.

A pair of solenoids 33-33 are suspended from the bracket v28 on opposite sides respectively of the latch and their cores are pro-` vided on their lower ends with discs 34-34 which engage the notches in the lateral arms of the latch respectively. The coils 35-35 of the solenoid are connected in the respective parallel circuits of the heaters, one terminal of each coil being connected to the terminal of the last heaterY in its respective circuit. The other terminals of the coils of the solenoids are connected together at 36 and to an animeter or other current indicating device at 37, the other terminal of which is connected bywire 38 to ground at 39,. I y

When the current is @if and the @entamer open the in its centralit-tiered iitlti-y l tion as shown in the drawing, and when the contacter is closed and the heater circuit intact, the latch remains in the intermediate position but is raised by 'the cores ot the solenoids to its upper position.

In the event of a ground in either of the heater circuits, one of the solenoid coils will be Cle-energized but not the other, and hence its core will drop tilting the latch and permitting the cut-out switch to close and shortcircuit the contactor coil, thus opening the heater circuits. rIhus during normal operation, the latch will merely reciprocate in a vertical direction slightly raising and lowering the `movable member ot the cut-out switch but without permitting it to close. But in the event of a ground while the heating current is on, it immediately tilts permitting the contacter to be opened.

For convenience in restoring the arm of the switch to normal position, and permitting` the latch to resume its intermediate position, the arm 24 is provided with a pivoted finger piece 40 which extends through a hole 41 in a brace 412 connected between the upper end of bracket 28 and the outer end thereof.

The indicator 37, which is exposed for observation will show a ground. in the heater circuits. Obviously the condition ot the cir cuit could be indicated by noting the position of the latch or the latter might carry or operate an indicator or signal in some exposed position.

I claim:

l. In a thermostatically constructed heater system 'for electric cars and the like, a plurality of heaters arranged in two parallel circuits, an electro-magnetically controlled contactor controlling'the supply of current to said heaters, a thermostat normally controlling the circuito'f said contactor, a normally open switch adapted to short circuit the thermostat when closed, means normally holding the switch open, said means jointly controlled by the respective parallel heater circuits, whereby a short-circuit in either circuit will permit said switch to close.

2. In a thermostatically constructed heater system for electric cars and the like, a plurality of heaters arranged in two parallel heating circuits, an electro-magnetically controlled contactor controlling the supply oi. current to said heaters, a thermostat normally 'controllingl the circuit of said contacter, a normally7 open switch adapted to short-circuit the thermostat when closed, a latch normally holding the switch open, electro-magnetic coils -in the respective parallel heating circuits holding` said latch in an intermediate position when both said circuits are energized but permittingr it to .move from said position and release the switch when either of said circuits is cle-energized.

3. In apparatus of the class described, a plurality oit heaters arranged in two parallel heating circuits, an electro-magnetically operated contacter controlling the supply of current to said heaters, a thermostat normally controllingl the circuit of said contactor, a normally open switch adapted to short-circuit the thermostat when closed, electro-magnets the coils oi which are arranged in the respective parallel circuits, a latch engaging said switch and pivotally movable, the armatures of said electro-magnets engaging the latch to give it a bodily movement when the coils oi said electro-magnets are energized and deenergized together and to give it a tilting movement when die-energized singly.

4.. In an electric heating system, parallel heating circuits, a contacter controllingthe same, electromagnetic means operating the contacter, a cut-out switch controlling said perating means, a device normally holding the cut-out switch open, and coils in the respective parallel circuits jointly controlling said device.

5. In an elect-rie heating system, parallel heating circuits, a contacter l'or openingl and closing the same, electro-magnetically operated means operating the contacter, a cut-out switch controlling the circuit oi said means, a pair ol? electro-magnetic means respectively in said parallel heating circuits, and a tilting device normally holding the cut-out switch open controlled jointly by the last said electro-magnetic means. Y

G. In a heating system, parallel heating circuits, a cont-actor, electro-magnetic means ior operating the same, a cut-out switchfcontrolling the circuit oi? said means, a tilting and bodily movable device normally maintaining said switch open, and electro-11mg4 netic means respectively Vin said parallel circuits jointly giving said device a bodily movenient and severally a tilting movement.

7. In a. heating system, a pair oill parallel heating circuits, a contacter controlling the same, electro-maglietically operated means controlling the contacter, a cut-out controlling` the circuit oit said electro-magnetically operated means, said cut-out comprising a pivoted arm, a latch normally supporting said arm and having a bodily movement toward and from the same, anda tilting movement releasingl the arm, and electro-magnetic means in the respective parallel heating eircuits jointly controlling the bodily movement of the latch and severally tilting the same.

8. In a heating system of the class described, a pair ot parallel heating circuits, a contacter controlling` the same, electro-magnetic means controlling the contacter, a thermostat opening and closing the circuit of said electro-magnetic means, an automatic cut-out also controlling said circuit, a latch normally 'maintaining said cut-out switch open, and electro-magnetic devices arranged in said parallel circuits and jointly controlling said cut-out.

9. In a heating system of the class 'described, a pair of parallel heating circuits, a contactor opening and closingsaid circuits, electro-inagnetio means controlling the contacter, an automatic cut-out for sai-d electromagnetic means comprising a pivoted arm, a latch having a pin and slot connection to its support normally maintaining said arm in a position to open the switch, solenoids on opposite sides of the latch, the cores of which are loosely connected thereto and adapted to jointly reciprocate the latch and severally to tilt the same, the coils of said solenoids being connected to the respective parallel circuits.

WILLIAM G. HARTWIG. 

